In the production, processing and use of organic halogen compounds (HHC) and the elimination of HHC-containing products, there are produced waste substances, exhaust air and waste gases which are undesirable in the environment due to their HHC content.
In J. K. Musick, F. W. Williams, Ind. Eng. Chem., Prod. Res. Devel. 13, 1974, 175/9, a method of catalytic decomposition is proposed for the purification of waste gases and exhaust air. M. P. Manning, Hazard, Waste 1, 1984, 41/64 discloses oxidizing chlorinated hydrocarbons (CHC) catalytically on Cr.sub.2 O.sub.3 /.delta.-Al.sub.2 O.sub.3. For the special case of the removal of CHC from so-called dump gases (produced in recycle plants of domestic garbage, rubbish and trash), alkaline contact compositions are used (DE 34 47 066).
The disadvantages of the previously known methods for the decomposition of HHC are the following:
None of the catalytic methods known up to the present is able to decompose chlorinated fluorochlorohydrocarbons (FCHC). The previously known catalysts consist of materials (for instance Al.sub.2 O.sub.3, SiO.sub.2, Cr.sub.2 O.sub.3) which are deactivated by hydrogen fluoride--one of the products of the decomposition of FCHC (DE 25 14 585). The catalytic oxidation of CHC leads to the partial oxidation of hydrogen chloride to chlorine and can thus not be used for the purification of waste gases and waste air since chlorine--in contradistinction to HCl--cannot be removed by simple means (for instance, scrubbing with water). The formation of chlorine generally results in the deactivation of the catalyst and the liberation of injurious substances, such as chromyl chloride and copper chloride (G. Laidig et al., Erdol, Kohle, Erdgas, Petrochem. 34, 1981 329/36, 333/4).
The active components of the catalysts for the catalytic oxidation of CHC are frequently expensive (platinum metals) or toxic (oxides of chromium, nickel, cobalt and molybdenum).